X-ray tube with movable directing cone



Feb. 14, 1950 D. E. BERGGREN X-RAY TUBE WITH MOVABLE DIRECTING `GONE Filed May 10. 1946 2 7, n V 7 e 9 n n. 4 Q MM y 1 s 6 f 2 ,m fR N m M f s ,VA 6m m2 ww r .Wn PMA G m my, Nm 0 ET. RD Rm am D.w i. B U T Y A D. Y@ F0a w w m 4, w 1.. M w M F n Patented Feb. 14, 1950 X-RAY TUBE WITH MOVABLE DIRECTING CONE Detlof Emanuel Berggren, Eindhoven, Netherlands, assignor, by mcsne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application May 10, 1946, Serial No. 668,707 In the Netherlands June 19, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires June 19, 1961 3 Claims.

. i l l i* When treating with X-rays it is desirable that it should be possible for the direction of the cone of rays emitted by the tube to be greatly varied in order that the cone of rays may be moved into an optimum position relatively to the members to be subjected to radiation without the need for thebody of the patient to be moved into various undesired positions. If the radiation is carried out with a small X-ray tube the latter is generally adapted to move in such manner that any desired direction of rays can be obtained without much trouble. In larger systems in which the tube s not adapted to move in so many ways it is necessary to conform the position of the body of the patient to that of the tube and this often limits the possibilities of radiation.

vAs a rule, vertical shifting of the tube is pos sible and also rotation of the tube about its own axis or, if this latter possibility is not provided for, rotation of the localiser about the axis of the tube. Rotation of the tube about an axis normal to the plane passing through the axes of the tube and the cone of rays is frequently impossible. Substantially such movement is always impossible with apparatus in which the tube extends forward from a vertical wall behind which the electric system is arranged. In the tube whilst being adapted to be raised and lowered and rotate about its own axis cannot rock. Indeed, if this possibility were provided for it would often still be impossible to bring the focal spot sufficiently near to the member to be subjected to radiation since the tube would be in the way of the body of the subject.

The present invention attends to the need for choosing the direction of the cone of rays so as to be optimum. It relates to an X-ray tube provided with a protective sheath, the localiser being movably secured to this sheath. According to the invention, the localiser is so secured to the sheath as to be adapted to rock around an axis inclined at right angles to the axis of the X-ray tube. In order to prevent the axis of the localiser from falling outside the focal spot of the X-ray tube during this rocking movement care is taken that the localiser is subjected at the same time to a translation in the axial direction of the tube.

In order that the invention may be clearly understood and readily carried into effect one practical example of a construction according to the invention in which various further amendments have been made will be described hereinafter with reference to the accompanying drawings, inwhich ligf` 1 Vis a longitudinal sectional view of a portion of an X-ray tube and its protective sheath and localiser.

Fig. 2 is a front elevation of the same parts.

In these drawings the X-ray tube is designated I, the protective sheath 2 and the localiser 3.

The X-ray tube is of the type in which only the cathode is insulated from earth to withstand high tension and the anode, which is arranged entirely at the end of the X-ray tube, is connected to earth when the tube is in use. The anode is constituted by a copper disc 4 which is set to form an angle of 45 with the axis and constitutes the bottom of a metal tube 5 forming part of the wall of the exhausted discharge vessel. On its inside surface the copper disc 4 carries a small plate 6 of tungsten which is struck by a beam of electrons and on which the focal spot is formed at T. The tube wall 5 and the anode 4 are enclosed with a small intermediate space 8 by a sheath 9. The intermediate sp-ace 8 may have circulating in it a liquid which conducts away the heat evolved in the anode while the tube is in use. The sheath 9 has a lead coating I0 which prevents X-rays `from emerging in undesirable directions.

Figure 1 only shows the front part of the X-ray tube. It extends to the left and is carried by a support or is fixed to a wall in such manner as to be adapted to be raised and lowered parallel with itself and to be rotated about its axis II. These movements permit the axis of the cone of X-rays, the centrally, to be rotated about an axis capable of being shifted parallel with itself. The invention also permits of the central ray being rotated about an axis normal to the former so that this ray can be caused to move through any point of the space.

In the construction shown in the drawing the protective sheath 2 is provided with a slide I2 which is adapted to shift endwise axially of the X-ray tube and in which the localiser 3 is pivoted at I3. The support in this movable slide ensures that the localiser can be subjected to a translation and the pivot I3 enables the rocking movement. The use of means enabling the two movements to be effected simultaneously in dependence on each other ensures that the axis of the localiser I4 which determines the location of the central ray is always directed towards the focal spot 1.

The said means include a directional arm which is secure to the localiser which in the practical construction shown is arranged for to be double and comprises the parts I5 and I6. This directional arm follows the rocking movement of the localiser and during the shifting of the slide I2 is controlled, by means of the guide of a pin in a 3. slot, by that part of the sheath 2 which is not adapted to shift axially of the X-ray tube, the stationary part, in such manner that the axis-of the localiser is always directed towards the focal spot.

If for this guiding a slot were formed in the sheath and a pin fitting into -it were provided on the directional arm the place of the localiser would be governed by the pivot and the slot. In such case the slot would 'have a curved shape comprising two symmetrical 'curves vinclined to each other at an acute angle. The construction is simplified if, as in the practical example, the stationary part of the sheath 2 has a laterally projecting pin Il, i3 whose axis passes through the focal spot and is parallel to the axis of rocking I9, this pin iitting into a slot 2Q, 2l formed in the directional arm parallel with the axis of the localiser.

When the localiser ismoved it rotates in the slide about the axis i@ and at the same time the slide I2 performs an endwise shifting movement dueto the directional arm I5, I8 'being retained aby the `pins Il' and i8 and the pivot of the localiser being forced to shift along the line 22.

The localiser might be arranged to be adapted to lrotate about an axis passing through the focal spot.` yIn this case, however, during the rocking movement the opening of the localiser is shifted relatively tc the sheath not only in a direction parallel to the axis of the-tube butalso in a direction normal thereto and it becomes more difficult to Akeep the connection of the localiser to the sheath `ray tight. In a `device according to the invention this latter condition is achieved by causing the localiser to rock outside the tube.

The pivot may be socket-shaped so as to permit'of the localiser being removed from the slide. In the construction .comprising a straight slot in the directional arm and a ,pin on thesheath the positionof the localiser is thus notyet entirely determined because the pivot and the slot'do not oppose a movement in the axial direction ofthe localiser. For this reason the practical example which kis provided Awith such a rocket-shaped .pivot comprises a runway 23 on the other side of the sheath 2, said runway carrying a relatively movable member 2d secured to the directional arm '15, I6. This runway prevents the localiser from being lifted orf the slide. It has such a curved shape that the distance of the centre of the sliding piece 2li at any point of the runway from the line of shifting 22 measured along the line :passing across the'point 'l is identical. 'SFricticnand wear oi'thefsliding piece andthe runway are reduced by the former being oonstr-uc'ted as a roller adaptedto rotate about an axis. It would yet be ei'rlcient if great friction were provided for, because in this case the position of the localiser would not be altered by any light lateral pressure. This need may be attended to EAAby lproviding a clamping device onthe vdirectional ar-m. In the practical example the'clampingideviceis formed by a screw 25 arranged in the bridge-piece 26 by which the two `parts l5 and I-Gare united. This clamping device permits of the sheath 2 being clamped to the localiser between'the pivot plane on one side and the pressure surface 21 of the clamping device on the other side.

This pressure surface may also serve as a runway during the rocking motion but in this caseit is not sosimple to construct the sliding piece' in the shape of a roller. It is vtherefore more Iefficient to provide the sheath 2 with an arc-shaped cam 28 whose upper side constitutes the pressure surface 21 for the clamping device and which has recessed init an arc-shaped slot 29 in which the roller v2'4 moves. yThe latter rolls over the lower side of the slot 29 with slight friction so that the localiser can be readily shifted. Once the localiser is moved into the desired position the screw 26 is slightly tightened and the localiser is thus clamped.

In order to assist in the shifting of the slide in the sheath 'its diameter is slightly smaller than the internal diameter of the sheath and the slide is surrounded by two bushings 30 and 3| which slide over the cylindrical inner surface of the sheath and may be resilient.

The sheath must have an elongated aperture so as to give the localiser suicient range but in so far as this aperture is wider than the localiser it is screened from` the X-rays by the slide.

Fig. 1 shows the localiser at one of its extreme positions. By vdotted lines the other extreme .position is` also indicated. The stationarypart of the `sheath r2 projects some distance Ifrom `the .2i-ray tube in'order to enable Athe slide to move aside to rsuch extentas is necessary for ythe rocking of the localiser. The location'of the slide whilst the localiser occupies its second extreme positionis kalso designated yby dotted lines.

Fig. 2 shows the vlocaliser at its .mid-position. Itl may also bel'seen :from this gurethat in the practicalexample the pivot is given'theshapeof a'ball and socket joint. This is not essential for theobtainment of thedesire'd rocking, for which a cylindrical pivot `would be sufficient, but it serves t0 enable the localiser to be pulled firmly into the socket more-easily bylmean's of'a clamping-device and to prevent X-rays from emerging on-all sides throughvjars.

What I yclaim is:

y1. X-ray apparatus comprising an .X-raytube provided with a target and .having aflongitudi-nal axis passing through vthe ztarget, :a 'fixed housing for Ythe X-ray tube, a beam localizing Imember having a beam axis intersecting'the longitudinal axis of the tube in 'a `focal spot on the target, a slide-member movable parallel to the :longitudinal axis ofthe tube, rmeans to rotatably couple'the beam localizing member to the slide comprising two intertting members connected to the slide member Land the beam localizin'g member respectively which constitute a pivot, and means coupling the beam localizingmember tothe Afixed housing for pivoting the beam localizing member about an axis perpendicular to the longitudinal axis of the tube and passing through the focal spot, whereby the Aaxis of vthe beam localizing member valways lpasses `throughfthe focal spot for all positions ofthe beam localizing-member.

2. X-ray apparatus comprising an X-ray tube provided with a ltarget l,and lhaving alongitudinal axis `passing through the target, `a `xed housing'for the X-ray tube, va beam localizing member having a `beam axis intersecting .the longitudinal-axis ofthe tube in a focalrspot on the target, a slide member movable parallel to the-longitudinal axis of the tube, .means to rotatably couple the beam localizing member to the slide member `comprising two inter'tting members connected to the slide member and the vbeam localizing member respectively constituting a ball and socket joint, and a supportingm'ember for the'beam localizing membervpivotally secured to the housing including apin member movable in a slot of said supporting member and a roller member movable along 8 cam surface of the housing whereby the beam localizingA lmember is rotatable about an axis perpendicular to and intersecting the longitudinal axis of the tube in the focal spot and the axis of the beam localizing member always passes through the focal spot for all positions of the beam localizng member.

3. X-ray apparatus comprising an X-ray tube provided with a target and having a longitudinal axis passing through the target, a xed housing for the X-ray tube, a beam localizing member having a beam axis intersecting the longitudinal axis of the tube in a focal spot on the target, a vslide member movable parallel to the longitudinal axis of the tube, means to rotatably couple the beam localizing member to the slide member comprising two interfltting members connected to the slide member and the beam localizing member respectively constituting a ball and socket joint, and a supporting member for said beam localizing member pivotally secured to the housing, including a pin member secured in the housing and slideable in a slot in the supporting member and a roller member movable in an arcuate guide secured to the housing whereby said beam localizing member is rotatable about an axis perpendicular to and intersecting the longitudinal axis of the tube in the focal spot and the axis of the beam localizng member always passes through the focal spot for all positions of the beam localizing member.

DETLOF EMANUEL BERGGREN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

